Conventional electric dust collectors, used to remove dust from exhaust fumes and exhaust gas from smelting furnaces (steel converters, cupolas, etc.), heat treatment ovens (annealing ovens etc.), ceramics ovens (cement kilns etc.), incinerators, drying ovens, and heat engines, are arranged so that exhaust fumes or exhaust gas passes between many closely spaced dust collecting electrodes. This causes a heavy pressure loss. To prevent an electric dust collector from being exposed to high temperatures, a cooler or the like, also serving as a heat recovery heat exchanger or a gas neutralizer, is normally installed immediately upstream of the electric dust collector, thus increasing pressure loss. Due to pressure loss thus caused, only aeration is not sufficient to emit exhaust fumes or exhaust gas, and accordingly, an exhaust fan is essential for the emission. Because of their exposure to corrosive gas and heat, exhaust fans fail so frequently that they require laborious maintenance and inspection.
In addition, conventional electric dust collectors have the following problems:
(i) Hammering performed to remove dust deposits from collecting electrodes dust to fly off. PA1 (ii) A high gas flow rate aerodynamically causes dust to fly off. PA1 (iii) Dust flies off due to reverse ionization occurring at a high dust electric resistance of more than 10.sup.12 .OMEGA..multidot.cm. PA1 (iv) Dust abnormally flies off due to a low dust electric resistance of less than 10.sup.4 .OMEGA..multidot.cm. PA1 (i) Exhaust fumes and exhaust gas humidity adjustment PA1 (ii) Dust collection at a high temperature around 360.degree. C. PA1 (iii) Wet-type dust collection PA1 (iv) Pulse charging
These problems reduce the rate of dust collection. To avoid the problems, conventional electric dust collectors require the following troublesome countermeasures:
It is an object of the present invention to provide an electric dust collector that needs no exhaust fan or special equipment dedicated to prevent dust from flying off.